Abstract: A gas turbine engine including: a casing in which is mounted at least one shaft for driving a fan solidly connected to a driving drum including blades to compress an airflow moving from upstream to downstream in the engine; and an axial retention mechanism, on standby, solidly connected to the casing and arranged to come into contact with the driving drum such as to prevent axial movement of the drum in event of breakage of the driving shaft.

Abstract: A method of monitoring twisting vibration of a rotary shaft of a turbine engine includes obtaining a vibratory acceleration signal from a sensor located on a stationary component of the turbine engine. This vibratory signal is characterized by a carrier frequency. The method also includes evaluating a frequency spectrum of the vibratory signal and searching for a pair of spectral lines of amplitudes greater than at least a first threshold. The lines are distributed in the spectrum on either side of the carrier frequency of the vibratory signal, and spaced apart therefrom by a twisting frequency of the shaft. Where appropriate, the method includes issuing a warning message.

Abstract: A decoupling system for a rotary shaft of an aircraft turbojet, the decoupling system including: a rolling bearing including rolling elements inserted between a first ring fastened to a stationary bearing support and a second ring mounted in a mounting chamber fastened to a rotary shaft; a transmission mechanism transmitting rotary torque from the rotary shaft to the second ring; a mechanism allowing the second ring to move radially relative to the mounting chamber when a static force associated with an unbalance affecting the rotary shaft exceeds a predetermined threshold; and a plurality of leaktight flexible bags interposed between the second ring and the mounting chamber and each including a heterogeneous structure including a porous capillary solid matrix and an associated liquid relative to which the matrix is lyophobic.

Abstract: A gas turbine engine including: a casing in which is mounted at least one shaft for driving a fan solidly connected to a driving drum including blades to compress an airflow moving from upstream to downstream in the engine; and an axial retention mechanism, on standby, solidly connected to the casing and arranged to come into contact with the driving drum such as to prevent axial movement of the drum in event of breakage of the driving shaft.

Abstract: A decoupling system for a rotary shaft of an aircraft turbojet, the decoupling system including: a rolling bearing including rolling elements inserted between a first ring fastened to a stationary bearing support and a second ring mounted in a mounting chamber fastened to a rotary shaft; a transmission mechanism transmitting rotary torque from the rotary shaft to the second ring; a mechanism allowing the second ring to move radially relative to the mounting chamber when a static force associated with an unbalance affecting the rotary shaft exceeds a predetermined threshold; and a plurality of leaktight flexible bags interposed between the second ring and the mounting chamber and each including a heterogeneous structure including a porous capillary solid matrix and an associated liquid relative to which the matrix is lyophobic.

Abstract: A method of monitoring twisting vibration of a rotary shaft of a turbine engine includes obtaining a vibratory acceleration signal from a sensor located on a stationary component of the turbine engine. This vibratory signal is characterized by a carrier frequency. The method also includes evaluating a frequency spectrum of the vibratory signal and searching for a pair of spectral lines of amplitudes greater than at least a first threshold. The lines are distributed in the spectrum on either side of the carrier frequency of the vibratory signal, and spaced apart therefrom by a twisting frequency of the shaft. Where appropriate, the method includes issuing a warning message.

Abstract: A shaft mounted to rotate with respect to another fixed or rotary element of a rotary engine to which the shaft is connected by at least one bearing, it being possible for the engine to operate in at least two different operating speeds, the shaft comprising a connection to the bearing that has a state of stiffness that varies with engine operating speed. The connection comprises a squirrel cage comprising at least two points of attachment, one to the bearing and one to the shaft, between which points there extends a flexible portion, the shaft comprises an actuator able to adopt at least two positions for controlling the state of stiffness of the squirrel cage, the actuator comprises a piston designed to be displaced by oil pressure in a chamber formed between the piston and shaft from a rigid state of stiffness position to a soft state of stiffness position.